Early pop-top, or tab-type, cans contained a ring member attached to a sealing member disposed over an opening in the top of a can containing a liquid. The can was opened by removing the combination of the ring member and sealing member. Primarily for environmental reasons, this combination was replaced with a generally elongated tab which is manually engaged and pivotally displaced about a rivet attaching the tab to the top of the can. The pivoting tab engages a sealing member and pivotally urges the sealing member into the can in opening the can. The tab and sealing member remain attached to the top of the can. The flat top of the can is provided with a weakened score line having a generally oval shape which is adapted to be broken from the can top and forced downwardly into the can by the upraised tab. This action forms a generally oval-shaped opening in the top of the can from which its liquid contents may be dispensed.
Opening a sealed can in this manner requires a certain amount of dexterity and strength generally not possessed by children and others having diseased or injured hands or long fingernails which the person does not want to damage or disfigure. To address these situations, various manual pop-top can openers have been proposed. The following list of patents is directed to can openers of this type:    U.S. Pat. No. 3,656,375    U.S. Pat. No. 3,724,297    U.S. Pat. No. 4,120,216    U.S. Pat. No. 4,133,228    U.S. Pat. No. 4,253,352    U.S. Pat. No. 4,373,223    U.S. Pat. No. 4,524,646    U.S. Pat. No. 4,583,429    U.S. Pat. No. 4,617,842    U.S. Pat. No. 4,864,898
All of the above-listed can openers are designed to open a sealed aperture in the top of the can. However, none of these openers provides for normal flow of the liquid contents from the can because of the presence of an air lock formed within the can when it is inverted to pour out its contents. The air lock results in a reduced, irregular discharge of the liquid contents from the can. The present invention prevents the formation of an air lock in the opening of a sealed can for facilitating discharge of the liquid contents in a uniform, maximum flow rate from the can.